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The DOE Science News Source is a Newswise initiative to promote research news from the Office of Science of the DOE to the public and news media.
  • 2017-03-09 08:05:43
  • Article ID: 670861

Cracking the Mystery of Perfect Efficiency: Investigating Superconductors

From the turn of the last century to today, scientists have explored why superconductors never lose current.

  • Credit: Image is taken from the Report of the Basic Energy Sciences Workshop on Superconductivity, May 8-11, 2006

    This figure shows how electrons pair up to cause superconductivity. Instead of traveling independently, the electrons couple into pairs that flow through metal without resistance.

  • Credit: Image is taken from the Report of the Basic Energy Sciences Workshop on Superconductivity, May 8-11, 2006

    In copper and iron-based superconductors, the spins on adjacent sites have north and south poles that alternate directions. Scientists think that the ordering of these magnetic poles may affect the electrons' interactions.

In 1911, physicist Heike Kamerlingh Onnes aimed to lower mercury’s temperature to as close to absolute zero as possible. He hoped to win a disagreement with Lord Kelvin, who thought metals would stop conducting electricity altogether at extremely low temperatures. Carefully manipulating a set of glass tubes, Kamerlingh Onnes and his team lowered the mercury’s temperature to 3 K (-454 F). Suddenly, the mercury conducted electricity with zero resistance. Kamerlingh Onnes had just discovered superconductivity.

This single finding led to a worldwide investigation that’s spanned a century. While it resolved one scientific debate, it created many more. The Department of Energy’s Office of Science and its predecessors have spent decades supporting scientists investigating the mystery of why superconductivity occurs under a variety of circumstances.

The answer to this question holds major opportunities for scientific and technological development. About six percent of all electricity distributed in the U.S. is lost in transmission and distribution. Because superconductors don’t lose current as they conduct electricity, they could enable ultra-efficient power grids and incredibly fast computer chips. Winding them into coils produces magnetic fields that could be used for highly-efficient generators and high-speed magnetic levitation trains. Unfortunately, technical challenges with both traditional and “high temperature” superconductors restrict their use.

“To the extent that Tesla and Edison introducing the use of electricity revolutionized our society, ambient superconductivity would revolutionize it once again,” said J.C. Séamus Davis, a physicist who works with the Center for Emergent Superconductivity, a DOE Energy Frontier Research Center.

The How and Why of Superconductivity

Kamerlingh Onnes’ discovery set off a flurry of activity. Despite his grand visions, most of what scientists found only reinforced superconductors’ limitations.

One of the first big breakthroughs came nearly half a century after Kamerlingh Onnes’ initial finding. While most researchers thought superconductivity and magnetism couldn’t co-exist, Alexei A. Abrikosov proposed “Type II” superconductors that can tolerate magnetic fields in 1952. Abrikosov continued his research at DOE’s Argonne National Laboratory (ANL) and later won the Nobel Prize in Physics for his contributions.

The next big leap came in 1957, when John Bardeen, Leon Cooper, and John Robert Schrieffer proposed the first theory of why superconductivity occurs. Their theory, made possible by the support of DOE’s predecessor, the Atomic Energy Commission, also won them the Nobel Prize in physics.

Their theory contrasts how some metals work under normal conditions with how they act at extremely low temperatures. Normally, atoms are packed together in metals, forming regular lattices. Similar to the spokes and rods of Tinkertoys, the metals’ positively charged ions are bonded together. In contrast, negatively charged free electrons (electrons not tied to an ion) move independently through the lattice.

But at extremely low temperatures, the relationship between the electrons and the surrounding lattice changes. A common view is that the electrons’ negative charges weakly attract positive ions. Like someone tugging the middle of a rubber band, this weak attraction slightly pulls positive ions out of place in the lattice. Even though the original electron has already passed by, the now displaced positive ions then slightly attract other electrons. At near absolute zero, attraction from the positive ions causes electrons to follow the path of the ones in front of them. Instead of travelling independently, they couple into pairs. These pairs flow easily through metal without resistance, causing superconductivity.

Discovering All-New Superconductors

Unfortunately, all of the superconductors that scientists had found only functioned near absolute zero, the coldest theoretically possible temperature.

But in 1986, Georg Bednorz and K. Alex Müller at IBM discovered copper-based materials that become superconducting at 35 K (-396 F). Other scientists boosted these materials’ superconducting temperature to close to 150 K (-190 F), enabling researchers to use fairly common liquid nitrogen to cool them.

In the last decade, researchers in Japan and Germany discovered two more categories of high-temperature superconductors. Iron-based superconductors exist in similar conditions to copper-based ones, while hydrogen-based ones only exist at pressures more than a million times that of Earth’s atmosphere.

But interactions between the electron pairs and ions in the metal lattice that Bardeen, Cooper, and Schrieffer described couldn’t explain what was happening in copper and iron-based high temperature superconductors.

“We were thrown into a quandary,” said Peter Johnson, a physicist at Brookhaven National Laboratory (BNL) and director of its Center for Emergent Superconductivity. “These new materials challenged all of our existing ideas on where to look for new superconductors.”

In addition to being scientifically intriguing, this conundrum opened up a new realm of potential applications. Unfortunately, industry can only use “high-temperature” superconductors are for highly specialized applications. They are still too complex and expensive to use in everyday situations. However, figuring out what makes them different from traditional ones may be essential to developing superconductors that work at room temperature. Because they wouldn’t require cooling equipment and could be easier to work with, room temperature superconductors could be cheaper and more practical than those available today.

A Shared Characteristic

Several sets of experiments supported by the Office of Science are getting us closer to finding out what, if anything, high-temperature superconductors have in common. Evidence suggests that magnetic interactions between electrons may be essential to why high-temperature superconductivity occurs.

All electrons have a spin, creating two magnetic poles. As a result, electrons can act like tiny refrigerator magnets. Under normal conditions, these poles aren’t oriented in a particular way and don’t interact. However, copper and iron-based superconductors are different. In these materials, the spins on adjacent iron sites have north and south poles that alternate directions – oriented north, south, north, south and so on.

One project supported by the Center for Emergent Superconductivity examined how the ordering of these magnetic poles affected their interactions. Scientists theorized that because magnetic poles were already pointing in opposite directions, it would be easier than usual for electrons to pair up. To test this theory, they correlated both the strength of bonds between electrons (the strength of the electron pairs) and the direction of their magnetism. With this technique, they provided significant experimental evidence of the relationship between superconductivity and magnetic interactions.

Other experiments at a number of DOE’s national laboratories have further reinforced this theory. These observations met scientists’ expectations of what should occur if superconductivity and magnetism are connected.

Researchers at ANL observed an iron-based superconductor go through multiple phases before reaching a superconducting state. As scientists cooled the material, iron atoms went from a square structure to a rectangular one and then back to a square one. Along the way, there was a major change in the electrons’ magnetic poles. While they were originally random, they assumed a specific order right before reaching superconductivity.

At DOE’s Ames Laboratory, researchers found that adding or removing electrons from an iron-based superconducting material changed the direction in which electricity flowed more easily. Researchers at BNL observed that superconductivity and magnetism not only co-exist, but actually fluctuate together in a regular pattern.

Unfortunately, electron interactions’ complex nature makes it difficult to pinpoint exactly what role they play in superconductivity.

Research at BNL found that as scientists cooled an iron-based material, the electron spins’ directions and their relationship with each other changed rapidly. The electrons swapped partners right before the material became superconducting. Similarly, research at ANL has showed that electrons in iron-based superconductors produce “waves” of magnetism. Because some of the magnetic waves cancel each other out, only half of the atoms demonstrate magnetism at any one time.

These findings are providing new insight into why superconductors behave the way they do. Research has answered many questions about them, only to bring up new ones. While laboratories have come a long way from Kamerlingh Onnes’ hand-blown equipment, scientists continue to debate many aspects of these unique materials.

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Rutgers Scientists Discover 'Legos of Life'

Rutgers scientists have found the "Legos of life" - four core chemical structures that can be stacked together to build the myriad proteins inside every organism - after smashing and dissecting nearly 10,000 proteins to understand their component parts. The four building blocks make energy available for humans and all other living organisms, according to a study published online today in the Proceedings of the National Academy of Sciences.

Small Hydroelectric Dams Increase Globally with Little Research, Regulations

University of Washington researchers have published the first major assessment of small hydropower dams around the world -- including their potential for growth -- and highlight the incredibly variability in how dams of varying sizes are categorized, regulated and studied.

Researchers Reveal How Microbes Cope in Phosphorus-Deficient Tropical Soil

A team led by the Department of Energy's Oak Ridge National Laboratory has uncovered how certain soil microbes cope in a phosphorus-poor environment to survive in a tropical ecosystem. Their novel approach could be applied in other ecosystems to study various nutrient limitations and inform agriculture and terrestrial biosphere modeling.

Scientists Discover Material Ideal for Smart Photovoltaic Windows

Researchers at Berkeley Lab discovered that a form of perovskite, one of the hottest materials in solar research due to its high conversion efficiency, works surprisingly well as a stable and photoactive semiconductor material that can be reversibly switched between a transparent state and a non-transparent state, without degrading its electronic properties.

Biofuels Feedstock Study Supports Billion-Ton Estimate

Can farmers produce at least 1 billion tons of biomass per year that can be used as biofuels feedstock? The answer is yes.

On the Rebound

New research from the U.S. Department of Energy's Argonne National Laboratory and Stanford University has found that palladium nanoparticles can repair atomic dislocations in their crystal structure, potentially leading to other advances in material science.

Coupling Experiments to Theory to Build a Better Battery

A Berkeley Lab-led team of researchers has reported that a new lithium-sulfur battery component allows a doubling in capacity compared to a conventional lithium-sulfur battery, even after more than 100 charge cycles.

DRIFTing to Fast, Precise Data

Non-destructive technique identifies key variations in Alaskan soils, quickly providing insights into carbon levels.

A Shortcut to Modeling Sickle Cell Disease

Using Oak Ridge National Laboratory's Titan supercomputer, a team led by Brown University's George Karniadakis devised a multiscale model of sickle cell disease that captures what happens inside a red blood cell affected by the disease.

Remotely Predicting Leaf Age in Tropical Forests

New approach offers data across species, sites, and canopies, providing insights into carbon uptake by forests.

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Theoretical Physicist Elena Belova Named to Editorial Board of Physics of Plasmas

Theoretical physicist Elena Belova named to editorial board of Physics of Plasmas

Superconducting X-Ray Laser Takes Shape in Silicon Valley

An area known for high-tech gadgets and innovation will soon be home to an advanced superconducting X-ray laser that stretches 3 miles in length, built by a collaboration of national laboratories. On January 19, the first section of the machine's new accelerator arrived by truck at SLAC National Accelerator Laboratory in Menlo Park after a cross-country journey that began in Batavia, Illinois, at Fermi National Accelerator Laboratory.

Kelsey Stoerzinger Earns Young Investigator Lectureship

Kelsey Stoerzinger, Pauling Fellow at Pacific Northwest National Laboratory, is one of the 2018 Caltech Young Investigator Lecturers in Engineering and Applied Physics.

North Dakota State University Joins Two National Distributed Computing Groups

The NDSU Center for Computationally Assisted Science and Technology (CCAST) joins OSG (Open Science Grid) and XSEDE (Extreme Science and Engineering Discovery Environment).

DOE Announces Funding for New HPC4Manufacturing Industry Projects

The Department of Energy's Advanced Manufacturing Office (AMO) today announced the funding of $1.87 million for seven new industry projects under an ongoing initiative designed to utilize DOE's high-performance computing (HPC) resources and expertise to advance U.S. manufacturing and clean energy technologies.

DOE Announces First Awardees for New HPC4Materials for Severe Environments Program

The Department of Energy's Office of Fossil Energy (FE) today announced the funding of $450,000 for the first two private-public partnerships under a brand-new initiative aimed at discovering, designing and scaling up production of novel materials for severe environments.

Two Argonne Scientists Recognized for a Decade of Breakthroughs

Two scientists with the U.S. Department of Energy's (DOE) Argonne National Laboratory have been named to the Web of Science's Highly Cited List of 2017, ranking in the top 1 percent of their peers by citations and subject area. Materials Scientist Khalil Amine and Energy and Environmental Policy Scientist David Streets say they are thrilled to see their work -- and the laboratory -- recognized in such a way.

Argonne Welcomes Department of Energy Secretary Perry

U.S. Department of Energy Secretary Rick Perry visited Argonne National Laboratory yesterday, getting a first-hand view of the multifaceted and interdisciplinary research program laboratory of the Department.

Argonne names John Quintana Deputy Laboratory Director for Operations and COO

John Quintana has been named Deputy Laboratory Director for Operations and Chief Operations Officer (COO) of the U.S. Department of Energy's (DOE) Argonne National Laboratory.

Developing Next-Generation Sensing Technologies

Recently, the Advanced Research Projects Agency-Energy (ARPA-E) announced $20 million in funding for 15 projects that will develop a new class of sensor systems to enable significant energy savings via reduced demand for heating and cooling in residential and commercial buildings.

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Exploring Past, Present, and Future Water Availability Regionally, Globally

New open-source software simulates river and runoff resources.

Arctic Photosynthetic Capacity and Carbon Dioxide Assimilation Underestimated by Terrestrial Biosphere Models

New measurements offer data vital to projecting plant response to environmental changes.

DRIFTing to Fast, Precise Data

Non-destructive technique identifies key variations in Alaskan soils, quickly providing insights into carbon levels.

Superconducting Tokamaks Are Standing Tall

Plasma physicists significantly improve the vertical stability of a Korean fusion device.

Graphene Flexes Its Muscle

Crumpling reduces rigidity in an otherwise stiff material, making it less prone to catastrophic failure.

Remotely Predicting Leaf Age in Tropical Forests

New approach offers data across species, sites, and canopies, providing insights into carbon uptake by forests.

What's the Noise Eating Quantum Bits?

The magnetic noise caused by adsorbed oxygen molecules is "eating at" the phase stability of quantum bits, mitigating the noise is vital for future quantum computers.

Rewritable Wires Could Mean No More Obsolete Circuitry

An electric field switches the conductivity on and off in atomic-scale channels, which could allow for upgrades at will.

Filtering Water Better than Nature

Water passes through human-made straws faster than the "gold standard" protein, allowing us to filter seawater.

Machine Learning Provides a Bridge to the Texture of the Quantum World

Machine learning and neural networks are the foundation of artificial intelligence and image recognition, but now they offer a bridge to see and recognize exotic insulating phases in quantum materials.


Wednesday January 17, 2018, 12:05 PM

Photographer Adam Nadel Selected as Fermilab's New Artist-in-Residence for 2018

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Wednesday January 17, 2018, 12:05 PM

Fermilab Computing Partners with Argonne, Local Schools for Hour of Code

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Wednesday December 20, 2017, 01:05 PM

Q&A: Sam Webb Teaches X-Ray Science from a Remote Classroom

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Monday December 18, 2017, 01:05 PM

The Future of Today's Electric Power Systems

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Monday December 18, 2017, 12:05 PM

Supporting the Development of Offshore Wind Power Plants

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Tuesday October 03, 2017, 01:05 PM

Stairway to Science

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Thursday September 28, 2017, 12:05 PM

After-School Energy Rush

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Thursday September 28, 2017, 10:05 AM

Bringing Diversity Into Computational Science Through Student Outreach

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Thursday September 21, 2017, 03:05 PM

From Science to Finance: SLAC Summer Interns Forge New Paths in STEM

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Thursday September 07, 2017, 02:05 PM

Students Discuss 'Cosmic Opportunities' at 45th Annual SLAC Summer Institute

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Thursday August 31, 2017, 05:05 PM

Binghamton University Opens $70 Million Smart Energy Building

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Wednesday August 23, 2017, 05:05 PM

Widening Horizons for High Schoolers with Code

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Saturday May 20, 2017, 12:05 PM

Rensselaer Polytechnic Institute Graduates Urged to Embrace Change at 211th Commencement

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Monday May 15, 2017, 01:05 PM

ORNL, University of Tennessee Launch New Doctoral Program in Data Science

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Friday April 07, 2017, 11:05 AM

Champions in Science: Profile of Jonathan Kirzner

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Wednesday April 05, 2017, 12:05 PM

High-Schooler Solves College-Level Security Puzzle From Argonne, Sparks Interest in Career

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Tuesday March 28, 2017, 12:05 PM

Champions in Science: Profile of Jenica Jacobi

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Friday March 24, 2017, 10:40 AM

Great Neck South High School Wins Regional Science Bowl at Brookhaven Lab

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Wednesday February 15, 2017, 04:05 PM

Middle Schoolers Test Their Knowledge at Science Bowl Competition

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Friday January 27, 2017, 04:00 PM

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Tuesday November 08, 2016, 12:05 PM

Internship Program Helps Foster Development of Future Nuclear Scientists

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Friday May 13, 2016, 04:05 PM

More Than 12,000 Explore Jefferson Lab During April 30 Open House

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Monday April 25, 2016, 05:05 PM

Giving Back to National Science Bowl

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Friday March 25, 2016, 12:05 PM

NMSU Undergrad Tackles 3D Particle Scattering Animations After Receiving JSA Research Assistantship

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Tuesday February 02, 2016, 10:05 AM

Shannon Greco: A Self-Described "STEM Education Zealot"

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Meet Robert Palomino: 'Give Everything a Shot!'

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University of Utah Makes Solar Accessible

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Friday November 16, 2012, 10:00 AM

Texas Tech Energy Commerce Students, Community Light up Tent City

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Wednesday November 23, 2011, 10:45 AM

Don't Get 'Frosted' Over Heating Your Home This Winter

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Friday April 22, 2011, 09:00 AM

First Polymer Solar-Thermal Device Heats Home, Saves Money

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Friday April 15, 2011, 12:25 PM

Like Superman, American University Will Get Its Energy from the Sun

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Thursday February 10, 2011, 05:00 PM

ARRA Grant to Help Fund Seminary Building Green Roof

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Tuesday December 07, 2010, 05:00 PM

UC San Diego Installing 2.8 Megawatt Fuel Cell to Anchor Energy Innovation Park

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Monday November 01, 2010, 12:50 PM

Rensselaer Smart Lighting Engineering Research Center Announces First Deployment of New Technology on Campus

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Friday September 10, 2010, 12:40 PM

Ithaca College Will Host Regional Clean Energy Summit

Ithaca College

Tuesday July 27, 2010, 10:30 AM

Texas Governor Announces $8.4 Million Award to Create Renewable Energy Institute

Texas Tech University

Friday May 07, 2010, 04:20 PM

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Wednesday May 05, 2010, 09:30 AM

National Engineering Program Seeks Subject Matter Experts in Energy

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Wednesday April 21, 2010, 12:30 PM

Students Using Solar Power To Create Sustainable Solutions for Haiti, Peru

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Wednesday March 03, 2010, 07:00 PM

Helping Hydrogen: Student Inventor Tackles Challenge of Hydrogen Storage

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Thursday February 04, 2010, 02:00 PM

Turning Exercise into Electricity

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Thursday November 12, 2009, 12:45 PM

Campus Leaders Showing the Way to a Sustainable, Clean Energy Future

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Tuesday November 03, 2009, 04:20 PM

Furman University Receives $2.5 Million DOE Grant for Geothermal Project

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Thursday September 17, 2009, 02:45 PM

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Wednesday September 16, 2009, 11:15 AM

Students Navigating the Hudson River With Hydrogen Fuel Cells

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